Marine pod drive system

ABSTRACT

A marine pod drive system for a marine vessel is disclosed. The marine pod drive system may a prime mover, a transmission unit and a first drive shaft. The transmission unit may be driven by the prime mover via a first drive shaft. The transmission unit further rotates a first intermediate shaft. The marine pod drive system further may include an underwater steerable structure comprising a first gearbox, a second intermediate shaft, a second gearbox and a propeller shaft. The first gearbox may include a first helical gear mounted on the first intermediate shaft and a second helical gear mounted on the second intermediate shaft. The rotation or torque from the first intermediate shaft is transmitted to the propeller shaft via the first gearbox, the second intermediate shaft, and the second gearbox. The propeller shaft may drive at least one propeller to produce thrust to drive the marine vessel.

TECHNICAL FIELD

The present disclosure generally relates to marine vessel. More, specifically, the present disclosure relates to a marine pod drive system of a marine vessel.

BACKGROUND

A marine vessel may use a pod drive system for propelling and maneuvering the vessel. The pod drive system may include one or more pod drive units for propelling the marine vessel. Each pod drive unit may include an inboard engine to drive an inboard transmission unit. The inboard engine and the inboard transmission unit are mounted inside a hull of the marine vessel. The inboard transmission unit may include a first bevel gear assembly. The inboard transmission is connected to and drives an underwater steerable gearcase. The underwater steerable gearcase is rotatably mounted through the hull and supports and drives one or more propellers. The inboard engine torque is transmitted from a substantially horizontal drive shaft through a first bevel gear assembly to a substantially vertical intermediate drive shaft. The substantially vertical intermediate shaft may extend downwardly through inboard transmission unit to the underwater steerable gearcase. The vertical intermediate shaft may transmit the engine torque through a second bevel gear assembly to a propeller shaft. In turn, the propeller shaft may drive one or more propellers to manuever the marine vessel in forward, rearward, or sideways direction. Further, the underwater steerable gearcase is rotated with respect to the hull to steer the marine vessel in left or right direction, instead of or in addition to, relying on a rudder.

However, a resistive force is felt by an operator when the operator tries to steer the marine vessel by rotating the underwater steerable gearcase. This resistive force is due to the inertia of the first bevel gear assembly of the inboard transmission unit.

SUMMARY

One or more embodiments of a marine pod drive system for driving a marine vessel are disclosed. The marine pod drive system includes a prime mover, a first drive shaft and a transmission unit. The transmission unit is driven by the prime mover via the first drive shaft. In an embodiment, the transmission unit includes a first bevel gear assembly. The marine pod drive system further includes a first intermediate shaft. The first intermediate shaft may be rotated by the transmission unit.

The marine pod drive system may also include an underwater steerable structure having a first gearbox, a second intermediate shaft, a second gearbox and an at least one propeller shaft. The first gearbox may be driven the first intermediate shaft. The first gearbox includes a first helical gear and a second helical gear. The first helical gear is mounted on the first intermediate shaft and the second helical gear is mounted on the second intermediate shaft. The first helical gear is in mesh with the second helical gear. The rotation or torque from the first intermediate shaft is transmitted to the second intermediate shaft via the first helical gear and the second helical gear of the first gearbox.

In an embodiment, the second intermediate shaft rotates the second gearbox which in turn drives the at least one propeller shaft. The least one propeller shaft is coupled with an at least one propeller. The at least one propeller shaft may be configured to rotate the at least one propeller to produce thrust to drive the marine vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a marine pod drive system according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary marine pod drive system 100 for a marine vessel according to an embodiment of the present disclosure. The marine vessel may include a boat, a ship, a watercraft or any other marine vessel. The marine pod drive system 100 may be configured to transmit torque from a prime mover to at least one propeller of a marine vessel. The marine pod drive system 100 is shown to include a prime mover 102, a first drive shaft 104, a transmission unit 106, a first intermediate shaft 108, an underwater steerable structure 110, and an at least one propeller 112.

In an embodiment, the marine pod drive system 100 may be configured to transfer the torque from the prime mover 102 to the at least one propeller 112 via the first drive shaft 104. The prime mover 102 may be a power source for providing rotary motion to the first drive shaft 104. For example, the prime mover 102 may be an engine, an electric motor, a hydraulic motor, a pneumatic motor, a crank shaft mechanism, and the like. The prime mover 102 is generally mounted with a hull 130 of the marine vessel.

The first drive shaft 104 may be configured to drive the transmission unit 106. The first drive shaft 104 is configured to transmit the torque from the prime mover 102 to the transmission unit 106. The transmission unit 106 may include a first bevel gear assembly 114. The first bevel gear assembly 114 may be configured to transmit the torque from the first drive shaft 104 to the first intermediate shaft 108. In an exemplary embodiment, the first drive shaft 104 is a generally horizontal shaft and the first intermediate shaft 108 is a generally vertical shaft. The bevel gear assembly is generally used where the torque or rotation is to be transmitted from a generally horizontal direction to a generally vertical direction or vice versa. In the present embodiment, the first bevel gear assembly 114 transmits the torque or rotation from the generally horizontally aligned first drive shaft 104 to the generally vertically aligned first intermediate shaft 108. It will be appreciated that any type of gear assembly can be used to transmit the torque from first drive shaft 104 to the first intermediate shaft 108.

The first intermediate shaft 108 may be configured to transmit the torque to the underwater steerable structure 110. The first intermediate shaft 108 may extend into the underwater steerable structure 110. The underwater steerable structure 110 may be configured to rotate with respect to the hull 130 about a substantially vertical axis 132. The underwater steerable structure 110 may be rotated to steer the marine vessel. The underwater steerable structure 110 may be rotated about the substantially vertical axis 132 by a steering mechanism (not shown in figure) known in the art.

The underwater steerable structure 110 includes a first gearbox 116, a second gearbox 118, a second intermediate shaft 120, and an at least one propeller shaft 122. The torque or rotation is transmitted to the first gearbox 116 via the first intermediate shaft 108. The first gearbox 116 may include a first helical gear 124 and a second helical gear 126. The first helical gear 124 and the second helical gear 126 may have a helix angle between 15 degree and 35 degree. However, it may be appreciated the value of the helix angle does not affect the functionality of the idea disclosed. In an embodiment, the helix angle of the first helical gear 124 and/or the second helical gear 126 may be 25 degree. The first helical gear 124 may be mounted on the first intermediate shaft 108 such that the first helical gear 124 rotates with the rotation of the first intermediate shaft 108. The first helical gear 124 may be mounted on the first intermediate shaft 108 by a mounting mechanism known in the art. For example, the first helical gear 124 may be mounted on the first intermediate shaft 108 by welding, splines, a key and slot mechanism or casting or any other mechanism know in the art. Similarly, the second helical gear 126 may be mounted on the second intermediate shaft 120.

In an embodiment, the second intermediate shaft 120 may be parallel to the first intermediate shaft 108 and is mounted inside the underwater steerable structure 110. The first helical gear 124 may be engaged with the second helical gear 126 to transmit torque from the first intermediate shaft 108 to the second intermediate shaft 120. The torque from the first gearbox 116 may be transmitted to the second gearbox 118 via the second intermediate shaft 120.

The second gearbox 118 may include a second bevel gear assembly 128. The second bevel gear assembly 128 is configured to transmit the torque from the second intermediate shaft 120 to the at least one propeller shaft 122. In an exemplary embodiment, the second intermediate shaft 120 may be a generally vertical shaft and the at least one propeller shaft 122 may be a generally horizontal shaft. The bevel gear assembly is generally used where the torque or rotation is to be transmitted from a generally horizontal direction to a generally vertical direction or vice versa. In the present embodiment, the second bevel gear assembly 128 transmits the torque or rotation from the generally vertically aligned second intermediate shaft 120 to the generally horizontally aligned propeller shaft 122. It may be appreciated that any type of gear assembly can be used to transmit the torque or rotation from the second intermediate shaft 120 to the at least one propeller shaft 122.

The at least one propeller shaft 122 may be coupled with the at least one propeller 112 and drive the at least one propeller 112. In an embodiment, there may be two propellers coupled with the at least one propeller shaft 122. The two propellers may be coupled to the at least one propeller shaft 122 such that one propeller rotates in opposite direction with respect to the direction of rotation of the other propeller. For example, one propeller may rotate in a clockwise direction while the other propeller rotates in the counter-clockwise direction. In another embodiment, both the propellers may be configured to rotate in the same direction that is either clockwise direction or counter clockwise direction.

The at least one propeller 112 may be configured to propel the marine vessel by producing forward or backward thrust. The forward or backward thrust is produced as the at least one propeller 112 rotates to push the water in a desired direction.

INDUSTRIAL APPLICABILITY

The present disclosure applies generally to the marine vessel and specifically applicable to the marine pod drive system 100. The marine pod drive system 100 is configured to drive the marine vessel by rotating the at least one propeller 112. The marine pod drive system 100 may include the prime mover 102 to drive the at least one propeller 112. The torque from the prime mover 102 may be transmitted to the at least one propeller 112 via the transmission unit 106, the first gearbox 116, the second gearbox 118, and the at least one propeller shaft 122. The prime mover 102 and the first transmission unit 106 may be mounted with the hull 130. The first gearbox 116, the second gearbox 118 and the at least one propeller shaft 122 may be mounted inside the underwater steerable structure 110.

The transmission unit 106 may include the first bevel gear assembly 114 to transmit torque from the first drive shaft 104 to the first intermediate shaft 108. The first gearbox 116 may include the first helical gear 124 and the second helical gear 126 to transmit the torque or rotation of the first intermediate shaft 108 to the second intermediate shaft 120. The use of helical gears in the first gearbox 116 reduces the gear ratio used in the first bevel gear assembly 114 of the transmission unit 106 and the second bevel gear assembly 128 of the second gearbox 118. Further, the use of helical gears may reduce the torque on the first intermediate shaft 108, thereby reducing the torque on the steering system to rotate the underwater steerable structure 110. The torque or rotation of the second intermediate shaft 120 may be transmitted to the at least one propeller shaft 122 via the second bevel assembly 128 of the second gearbox 118. The at least one propeller shaft 122 is coupled to the at least one propeller 112 for rotating the at least one propeller 112. The rotation of the at least one propeller 112 pushes the water to create a forward or backward thrust to propel the marine vessel.

Further, the marine vessel is steered by rotating the underwater steerable structure 110 about the vertical axis 132 in a horizontal plane with respect to the hull 130. The underwater steerable structure 110 is rotated by operating the steering mechanism (not shown in the figure) known in the art. When the underwater steerable structure 110 is rotated to steer the marine vessel, some of the rotational movement is transferred to the first bevel gear assembly 114. Therefore, the steering of the marine vessel is resisted by the inertia of the gears of the first bevel gear assembly 114. This inertial resisting force may be large when the gear ratio in the bevel gear assembly is large. The large inertial resisting force may provide a feeling of hard steering to the operator. The marine pod drive system 110 disclosed herein provides the first gearbox 116 having the first helical gear 124 and the second helical gear 126. This arrangement of the first helical gear 124 and the second helical gear 126 reduces the gear ratio in the first bevel gear assembly 114, thereby decreasing the inertial resisting force of the bevel gears in the first bevel gear assembly 114 during steering of the marine vessel. 

What is claimed is:
 1. A marine pod drive system for driving a marine vessel, comprising: a prime mover; a transmission unit configured to be driven by the prime move via a first drive shaft; a first intermediate shaft configured to be rotated by the transmission unit; an underwater steerable structure, the underwater steerable structure comprising: a first gearbox, the first gearbox is driven by the first intermediate shaft, the first gearbox comprising: a first helical gear mounted on the first intermediate shaft; and a second helical gear engaged with the first helical gear and configured to be rotated by the first helical gear; a second intermediate shaft, wherein the torque from the first intermediate shaft is transmitted to the second intermediate shaft via the first gearbox; a second gearbox configured to be rotated by the second intermediate shaft; at least one propeller shaft configured to be driven by the second gearbox; and at least one propeller configured to be rotated by the at least one propeller shaft. 